Re: [hylafax-users] faxmail fork bomb

[Ole Kaas <obk@xxxxxx>]

Den 22/04/2010 kl. 17.20 skrev Aidan Van Dyk:

> * Ole Kaas <obk@xxxxxx> [100422 11:10]:
>> Hello,
>> 
>> We received today an email in our email to fax gateway that turned faxmail into a fork bomb. It seems that it kept trying to decode the same attachment again and again - forking a new child every time. Maybe it would be a good idea to somehow limit the maximum number of forks that faxmail will do before giving up? Then we can try to find out if there's a bug in faxmail or the (MS generated) mail is malformed.   
> 
> Ole,
> 
> Any chance you have a copy of that email?   If so, I'ld love to get and
> see what the bug is..  faxmqil shouldn't just recurse indefinately on a
> message, it should be exactly proportional to the size of the mail
> message (and the maximum number of mime parts a message of size $X can
> contain).
> 
> Are you using plain faxmail, or using some wrapper scripts?

I have mailed the email to you privately. We use qmail, where the dot-qmail file runs a script that finds some user specific settings before running faxmail:

/usr/bin/faxmail $FAXMAILOPT -T -f Helvetica-Bold | /usr/bin/sendfax \
    -D \
    -i "$TAG" \
    -s a4 \
    -f "$RETURN" \

There are no loops or recursion in the script - only some if/then/else and database lookup. Curently the only extra option parsed to faxmail is "-N".

/Ole

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